A protester who has held a 24-hour vigil outside Parliament for four years won the High Court's permission yesterday to challenge changes to the law which could lead to his removal.
Because of the urgency of the case, three senior judges started hearing the full challenge brought by 56-year-old Brian Haw immediately after granting leave.
Mr Haw, a carpenter from Redditch, has been protesting in Parliament Square since June 2001, initially against Western sanctions on Iraq and later against the UK's involvement in the US-led war and its aftermath.
He sleeps in the Square and has built up a large display of anti-war banners, placards and flags, many presented by well-wishers.
He said before the hearing: "The Government clearly do not want me as a constant reminder of the immense suffering they are causing the people of Iraq.
"For centuries, British citizens have had the right to protest outside the mother of parliaments. Now this is to be left to the diktat of the police."
Richard Drabble QC, appearing for Mr Haw, said he was seeking "as a matter of some urgency" a declaration that Mr Haw did not need to apply for authorisation if he wishes to continue the demonstration he started some years ago.
Mr Drabble said Mr Haw was "a well-known protester" and committed Christian with a passion for peace and human rights. No-one had suggested that he posed a security problem.
The threat to his vigil arose after the Serious Organised Crime and Police Act became law earlier this year and a notice and authorisation regime was introduced under it, said Mr Drabble.
The result was that protesters had to obtain police permission before staging any demonstration in an area designated by Home Secretary Charles Clarke around the Houses of Parliament, including Parliament Square and Whitehall.
Section 130 (1) of the Act made it a criminal offence to demonstrate in a designated area "if, when the demonstration starts, authorisation has not been given under the Act", said Mr Drabble.
"At the heart of the case is the proposition that, on the ordinary principles of statutory construction, it is quite clear that the section does not apply to demonstrations which had already started before commencement (of the new Act)."
Mr Drabble said Mr Haw's solicitors wrote to the Home Secretary in April pointing this out, and attempts were then made to amend the law so that it did catch demonstrations which had already started.
But the attempt to modify the law was flawed and it still failed to catch Mr Haw, said Mr Drabble.
Both the Home Secretary and the Commissioner of the Metropolitan Police are resisting the legal challenge.
In 2002, Mr Haw successfully fought off an attempt by Westminster City Council to evict him on the grounds he was obstructing the highway. A High Court judge ruled that his right to freedom of speech and assembly under the European Convention on Human Rights outweighed any obstruction he was causing.
Nathalie Lieven, appearing for the Home Secretary, said the new law applied to continuing as well as new demonstrations and described the arguments being put forward by Mr Haw's legal team as "absurd".
Ms Lieven said Mr Haw's display of anti-war banners, placards and flags gave rise to a potential security risk.
Parliament had clearly intended the new law to apply to Mr Haw, and the most that could be said was that the parliamentary draftsman had made a mistake when using the word "starts".